Alkylation of paraffin hydrocarbons



Nov. 3o 1943.

A. V. GROSSE ET AL ALKYLATION OF PARAFFIN HYDROCARBONS Filed Nov. 17,1941 Patented Nov. 30, 1943 ALKYLATION or PARAFHN nYDaooAanoNs Aristid.V. Grosse, Bronxville, N. Y., and Carl B. Linn, Chicago, lll., assignorsto Universal Oil Products Company, Chicago, Ill., a corporation ofDelaware Application November 17, 1941, serial No. 419,386 e claims.y(ci. 26o-.aaah

This application is a continuation-impart of our co-pending applicationSerial No. 248,777, led December 31, 1938, now Patent No. 2,267,730,granted December 30, 1941.

This invention is more particularly concerned with the interaction ofisomeric or branched chain paraflin hydrocarbons and mono-oletnichydrocarbons in the presence of catalysts.

It is more specically concerned with a simple and easily regulatedprocess involving the use of a liquid catalyst which is only slightlyaltered in the course of the reactionsv and which catalyzes the desiredreactions with a maximum of eilciency.

Processes for the formation of higher molecular weight branched chainhydrocarbons from essentially straight -chain compounds or less highlybranched compounds are of present importance from the standpoint of themotor vfuel y industry which demands increasing quantities of isoparanswithin lthe boiling range vof gasoline and particularly iso-octanes,such as, for example, the 2,2,4-trimethyl pentane which forms thestandard of reference in rating the anti-knock valuev of gasolines.Considerable quantities ofbutanes and butenesare available asby-products from the cracking of petroleum fractions to producerelatively high primary yields of gasoline and by proper segregation ofbutanes and butenes' by solvent` extraction and fractionation methods,-particularly cuts are available for recombination to produce materialyields of the desired iso-octanes. Eiorts to alkylate normal butane withbutenes in the pres-A ence of catalysts have thus far failed unlessconcurrent isomerization ofthe normal butanes to isobutane occurs.However, isobutane fractions may be made to interact with butenes andparticularly isobutene in the presence of various catalysts to formvariable iso-octanes.

catalysts previously tried to eect the' alkylation of isoparaiinhydrocarbons with olefin hydrocarbons include sulfuric acid, phosphoricacid, aluminum chloride, and boron fluoride, all of which havedisadvantages which are in a large measure overcome by the use'of thecatalysts of the present invention. Sulfuric acid, for example, can notbe used to effect alkylation with ethylene and gives very poor yieldswhen pro pylene is used. Furthermore, this acid has a tendency tooxidize hydrocarbons with the formation of sulfur dioxide so that thecatalyst 1s gradually lost by reduction and the products of the reactionare contaminated with sulfur compounds and oxidation products.

-boron fluoride and minor amounts of hydrogen.

Phosphoric acid has a limited application but the reactions are notaccelerated to a practical degree unless undesirably high temperaturesare employed. Aluminum chloride and similar multivalent metal saltspresent the usual disadvantages inherent in the use of solid granularcatalysis in that the efliciency of the reactionis to some extentcontingent on the iineness of subdivision of the catalyst and thatrecovery of the i active salts from their sludges is difllcult andexpensive. The use of boron fluoride is not practical on account of thecost oi'this compound.

In one specific embodiment the present invention comprises a process foralkylating isoparaflin hydrocarbons with mono-olefinic hydrocarbons inthe presence o f liquid hydrogen fluoride under controlled conditions ofoperation.

We have determined that whereas previous work in alkylating variousclasses of yhydrocarbons with olefins has indicated that theY reactioncould be brought about in the presence of fluoride, the reactions arebetter brought about when using merely liquid anhydrous hydrogen uoride.'I'his catalyst is a liquid boiling at about 20 C. so that Ait can beused in an apparatus which is cooled to maintain temperatures below thispoint or can be used at higher temperatures if sufficient pressures aremaintained upon the apparatus. parafln at all times, polymerizationreactions and the formation of alkyl uorides are minimized so that theproducts consists principally of alkylated derivatives -of the originalisoparafns. The catalyst is not changed by oxidation.

or reduction and if lost mechanically it can be readily recovered andre-used while any alkyl iiuorides formed are readily decomposable.

In operating the present process, the preferred procedure is to agitatea'mixture of liquid hydrogen uoride and an isoparaiin and graduallyintroduce a mixture of an olefin and an soparaiin below the surface ofthe hydrogen fluorideisoparaflin mixture. In `the batch operation ofthis process, the agitation may be stopped and the upper hydrocarbonlayer fractionated to recover unchanged parains and the desiredalkyllated products. Obviously the process may be made continuous byproviding a mixing zone in which suincient time is given for thecompletion of the desired reaction followed by a settling zone fromwhich a hydrocarbon layer is Withdrawn and fractionated to recoverdesired al-A kylated products and parain for recycling, while Bymaintaining an excess of iso-l furic acid with iluorides such as afluoride of a l Group II metal, for example, calcium fluoride, althoughit will be obvious to those skilled in these types of operations thatthe preferred procedures outlined for batch and continuous operationsrespectively will need to be modified somewhat.

For the purpose of illustrating a characteristic apparatus hook-up inwhich the process may be conducted, the attached drawing showsdlagrammatically in general side elevation and by the use ofconventional figures an arrangement of interconnected units suitable forcontinuous operations. It is understood that minor features of apparatusconstruction may be modied with-- out departing essentially from thegenerally broad scope of the invention.

'Referring to the drawing, liquid isoparaiin hydrocarbons may beintroduced through line I containing valve 2 to line 3 containing valve4 leading to pump 5 while liquid hydrogen fluoride is introduced to line3 by way of line B containing valve 1. Pump 5 discharges through line 8containing valve 9, line 8 receiving a regulated and continuous streamof oleilns, or olens plus isoparafhns, from line I containing valve II,the mixture passing through line I2 containing valve I3 and through acooler I4 of any suitable construction and capacity for maintaining thetemperature of reaction below any desired level while at the same timepermitting time for the completion of the reactions. The reactionproducts follow line I5 containing valve I6 to a` re-v ceiver l1 inwhich a separation of hydrogen nuoride and hydrocarbons is eiected.. Thehydrogen fluoride is withdrawn from the receiver through a line I8containing valve I9 and returned by pump 2Il which discharges throughline 2i containing valve 22 into line 23 leading to the suction side ofpump' 5 so that the hydrogen-iluoride catalyst is completely recycled.

The hydrocarbon layer in the upper portion of receiver Il passes throughline 24 and valve 25 and enters fractionation column 26 containing areboiler 21, unconverted low boiling hydrocarbons being removed asoverhead while higher boiling aiityiated products or the reaction arewithdrawn through line 28 containing valve 29 from the bottom oi thecolumn.

The overhead products pass through line 30 containing valve 3| throughcondenser 32 and thence through run-down line 33 containing a valve 34to receiver 35 which has a. conventional gas release hne 36 containingvalve 31 and a liquid draw line 38 containing valves leading to a pump40 which discharges through line 4I containing valve 42 to storage ildesired. but ordinarilykthrough line 43 containing valve 44 and leadingto hne 2 3 t0 permit the further alkyiation of the paranin.

The exact temperatures and pressures which should. be employed whenalkylating various isoparailins with various oleflns will depend uponthe activity and physical characteristics of the hydrocarbons involvedso be obtained when conditions are rst determined in small scaleapparatus. As a rule. excessive elevated temperatures are not necessaryo r desirable and only suiilcient pressures should be that best resultswill,

used to prevent excessive evaporation of the catalyst or thehydrocarbons.

For the recovery for re-use of hydrogen fluoride which may combine witholeflns to form alkyl rluorides in 'the course of the alkylatingreactions, these uorides may be passed over granular iluoride's such ascalcium fluoride or aluminum luorides which decomposes them intohydrogen fluoride andthe corresponding oleflns. The mixture of olefinand hydrogen uoride is then passed over solid granular sodium orpotassium fluoride which forms addition compounds of the type NaF-HF.The olen liberated may be recycled for further use and the hydrogennuoride recovered from the double salt by heating.

The following experimental data is given by way of example to indicatethe results obtainable when utilizing the present process for alkylatingisobutane with butenes to form isooctanes. This example has been chosenbecause of its commercial importance and it is not to be inferred thatthe scope of the invention is limited in exact correspondence with thedata presented.

Concentration of hydrogen lfluoride To determine whether the anhydrousmaterial and the water solutions of hydrogen fluoride could be usedinterchangeably or with substantially equivalent eiects, tests wereconducted using 100% anhydrous material, a 90% aqueous solution, and a75% aqueous solution. An ap-` proximately molal equivalent mixture ofisobutane and isobutene was passed into the acids of varyingconcentration at temperatures from 20-30 C., the runs being made in acontinuously stirred pressure autoclave. Using 100% an hydrous hydrogenfluoride, the recovered hydrocarbon layerconsisted of 50-60% octanes owhich about half was 2,2,4-trimethyl pentane. The hydrocarbon layer wascompletely saturated and contained only 0.1% of fiuorine. With theaqueous solution and a molal ratio oi parain to oleiin of 1.5:1, thehydrocarbon layer consisted of 48% octanes and there was present 1% offluorine. With a 75% acid solution, an equivalent molal ratio ofparailin to olen and a temperature of 12 C., no alkylation occurred, butthere was considerable formation o! butyl uorides, isobutenes formingtertiary butyl uorides and normal butenes forming secondary butylfluorides.

Eect of temperature Using a -mixture of isobutane and isobutene in amolal ratio of 1.5:1 and 100% hydrogen fluoride, best results wereobtained at room temperature. At temperatures within the range of -50 to60 C., no alkylation occurred, but there was considerable polymerizationof isobutene. The hydrocarbon layer contained 2% iuorine; At atemperature of +90 C. utilizing sufficient pressure to maintain liquidphase and with a paraln-olen ratio of 1:3, the hydrocarbon productsconsisted of only 20% octanes and a large amount of more highlyalkylated derivatives. Temperatures as high as C. may be used, ifdesired, by suitable adjustment of time factor, olen-parain ratio, andamount of catalYSt used.

Eject lof paraHn-olefn ratio s Using a molal ratio of parain to olefinof 3:1,

temperatures from 20-30 C. and 100% hydrogen iiuoride, 65% ofhydrocarbon product boiled with- Efect of contact time This factor wasfound to tary with the teinperature employed and the reactivity ofvari-4 ous isoparailns and. olens which may be brought together.

We claim as our invention: 1 1. A process for synthesizing hydrocarbonswhich comprises reacting an isoparaiiln withan olenn in the presence ofan alkylating catalyst consisting essentially oi hydrogen iluoride asits en active ingredient, 4said hydrogen iiuoride being generated insitu by interaction oi' a strong mineral acid with a fluoride underconditions 'suitable for generating hydrogen uoride and-for alkylatingsaid isoparamn.

2. A process ior synthesizing u which comprises reacting an isoparaiiinwith an olenn in the presence oi.' an alkyiating catalyst consistingessentially of hydrogen uoride as its active ingredient. said hydrogennuoride being .o

generated in situ by interaction of sulfuric acid with a iluoride of ametal under conditions suitable i'or generating hydrogen iiuoride andfor alkylating said isoparaiiln.

3, A process io'r synthesizing hydrocarbons u which comprises reactingan iscparaiiln with an oleilninthepresenceoianalhlatingcatalystconsisting essentially of hydrogen iluoride as its` active ingredient,said hydrogen iiuoride being lenerated in situ by interaction oisulfuric acid with a iiuoride of a Group Il metal under conditionssuitable for generating hydrogen fluoride and for alkylating saidisoparamn.

4.' A process for synthesizing hydrocarbons which comprises reactingan'isoparamn with an olenn in the presence otan alkylating Icatalystconsisting essentially of hydrogen iiuoride as its active ingredient,said hydrogen iluoride being generated in situ by interaction ci'sulfuric acid with calcium nuoride imder conditions suitable forgenerating hydrogen iluoride and for aikylat.- ins said isoparamn.

5. A process -for synthesizing hydrocarbons which comprises reacting anisoparamn with an olenn in the presence of an alkylating catalystconsisting essentially oi hydrogen iluoride 'as its active ingredient,said hydrogen nuorlde being Zeneiated in situ by interaction of sulfuricacid with calcium nuoride at a temperature between about 20' and about100 C. under a pressure sumcient to maintain in substantially liquidphase a substantial proportion of the hydrocarbons and hydrogeniluoride.

8. A process ior synthesizing hydrocarbons which comprises reactingisobutane with a normally gaseous olenn in the presence oi an alkylatingcatalyst consisting essentially oi' hydrogen iiuoride as its activeingredient, said hydrogen iiuoride being generated in situ byinteraction oi sulfuric'acid with calcium iloride at a teinperaturebetween about 20 and about-100? C.

a'pressure sumcient to maintain in substantially liquid phase asubstantial'proportion oi' the hydrocarbons i'luoride.4 Y

` ARIBTID v. GROSSE.

CARL B. LlNN.

